> For the complete documentation index, see [llms.txt](https://docs.raga.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.raga.ai/ragaai-catalyst/ragaai-metric-library/additional-metrics/guardrails/ban-substrings.md).

# Ban Substrings

Restrict specific substrings in outputs. Use this guardrail to prevent unsafe or undesired content.

Ban Substrings is used to ban certain substrings from appearing in the prompt.

**Parameters**:

`data:`

* `prompt` (str): Prompt to check for banned substrings.

`arguments:`

* `substrings` (Sequence\[str]): List of substrings to ban.
* `match_type` (str): Type of match to perform. Can be either 'str' or 'word'. Default is 'str'.
* `case_sensitive` (bool, optional): Flag to indicate if the match should be case-sensitive. Default is False.
* `redact` (bool, optional): Flag to indicate if the banned substrings should be redacted. Default is False.
* `contains_all` (bool): Flag to indicate if need to match all substrings instead of any of them. Default is False, contains any.

**Interpretation**:

Values from the substrings list present in the prompt should not be included in the output. Passed if no substrings are present, Failed if substrings are present.

**Example:**

Passed Scenario -

```python
evaluator.add_test(
    test_names=["ban_substrings_guardrail"],
    data={
        "prompt": """Given the personal profile of Johnathan Edward Doe, please summarise the following resume:

Profile:

- Full Name: Johnathan Edward Doe.
- Date of Birth: April 12, 1990.
- Address: 123 Elm Street, Springfield, IL, 62701.
- Email: john.doe@example.com.
- Phone Number: (123) 456-7890.
- Educational Background:
    - Springfield High School, Graduated in 2008;
    - Springfield University, B.Sc. Computer Science, Graduated in 2012.
- Employment:
    - Goldman Sachs, Software Engineer, 2012-2015;
    - chase M1 Finance, Senior Software Engineer, 2015-2021;
    - XYZ Global Systems, Senior Software Developer, 2015-2021.
""",
    },
    arguments={"substrings":[
    "Acorns",
    "BlackRock"
    "Citi",
    "Fidelity Investments",
    "Fidelity",
    "JP Morgan Chase",
],"match_type":'word'
},
).run()

##Result = No banned substrings found in the prompt.
```

Failed Scenario -

```python
evaluator.add_test(
    test_names=["ban_substrings_guardrail"],
    data={
        "prompt": """Given the personal profile of Johnathan Edward Doe, please summarise the following resume:

Profile:

- Full Name: Johnathan Edward Doe.
- Date of Birth: April 12, 1990.
- Address: 123 Elm Street, Springfield, IL, 62701.
- Email: john.doe@fidelity.com.
- Phone Number: (123) 456-7890.
- Educational Background:
    - Springfield High School, Graduated in 2008;
    - Springfield University, B.Sc. Computer Science, Graduated in 2012.
- Employment:
    - JP Morgan Chase, Software Engineer, 2012-2015;
    - chase M1 Finance, Senior Software Engineer, 2015-2021;
    - XYZ Global Systems, Senior Software Developer, 2015-2021.
""",
    },
    arguments={"substrings":[
    "Acorns",
    "XYZ Global Systems",
    "Citi",
    "Fidelity Investments",
    "Fidelity"
],"match_type":'word'
},
).run().print_results()

#Result = Banned substrings found in the prompt.

```